THEREOF FOR PERFORMING CONTINUOUS NERVE BLOCK

PROCEDURES

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 62/884,857, titled “COILED OVER-THE-NEEDLE CATHETER AND METHODS OF USE THEREOF FOR PERFORMING CONTINUOUS NERVE BLOCK PROCEDURES” and filed on August 9, 2019, the entire contents of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to systems, devices and methods for the delivery of local anesthetics. In particular, the present disclosure relates to systems, devices and methods for the delivery of a continuous nerve block.

A regional anesthesia/nerve block involves the use of a local anesthetic to block sensations of pain from a large area of the body, such as an arm or leg or the chest/abdomen. A local anesthetic is injected near a specific nerve or bundle of nerves to block sensations of pain from the area of the body supplied by the nerve. Nerve blocks are most commonly used for surgery on the arms and hands, the legs and feet, the groin, abdomen or the face. The duration of the nerve block is limited by the duration of the effect of the local anesthetic injected.

Since the duration of action of local anesthetic drugs is limited, it is often desirable to provide regional anesthesia on a continual basis as an infusion through a catheter, particularly in the postoperative settings for pain management. Continuous regional anesthesia, in the post-surgical patients, can provide excellent analgesia without systemic side effects associated with narcotics and other systemic analgesics.

Continuous regional anesthesia and analgesia requires the introduction of a peripheral nerve catheter adjacent to the desired nerve/nerve plexus or in the fascial plane containing the neural elements. The desired nerve or nerve plexus is localized by applying milliampere levels of current to an insulated needle. The nerve is located by gradually advancing the insulated needle until the applied current induces visible muscle contraction. Alternatively, ultrasound imaging may be used to visualize the nerve/nerve plexus or the fascial plane, and the needle is advanced to this target under direct ultrasound visualization. In some situations, practitioners combine both techniques of electrical stimulation and ultrasound imaging to confirm needle placement.

In order to achieve anesthesia/analgesia, the tip of the insulated needle is typically placed within millimeters of the nerve or nerve plexus. For the continuous nerve block technique, the distal end of the catheter is also placed within millimeters of the target and is required to remain in this location for the duration of use. During a procedure involving a continuous nerve block, movement of the needle or the catheter can reduce or eliminate the effect of the regional anesthetic, damage the nerve, or both. As a result, such methods only permit a very small margin for error on the part of the anesthesiologist as well as the nerve block system (needle and catheter) that is used.

Currently, the most common technique for inserting catheters for continuous nerve blocks is to feed a catheter though a needle (CTN). An insulated epidural/Touhy type needle is inserted and placed in close proximity of the targeted nerve - this placement is either confirmed by electrical stimulation of the nerve or by ultrasound visualization or a combined technique. This approach allows for the catheter to be fed through the needle and placed in proximity of the targeted nerve.

The catheter is typically threaded beyond the tip of the needle by 2-4 cm, which maintains proximity to the target but reduces accidental displacement of the catheter from close proximity of the nerve due to movement of the patient. Currently there are a number of different catheters available for CTN systems. Stimulating catheters allow for confirmation of accuracy of the catheter placement by electrical stimulation.

CTN catheters have the following associated advantages: (i) they are the most commonly used and familiar technique, (ii) the operator can control the depth of catheter beyond the needle tip, (iii) they allow the operator to leave some slack (2-4 cm) along the target to avoid inadvertent displacement of the catheter from the target.

An alternative approach has been borrowed from the commonly used intravenous catheter design, where the catheter is fitted over the needle. With the catheter-over-needle systems (CON) the needle and catheter assembly are introduced and advanced toward the targeted nerve together as a unit. Once the position of the needle tip is confirmed (electrical stimulation and/or ultrasound imaging) the needle can be removed leaving the catheter at the desired site in close proximity to the nerve.

As there is no need for threading a catheter, one advantage of this design is that it is may require less time and prove easier to use. In catheter- over-the needle systems, the diameter of the catheter is larger than the needle such that the puncture hole diameter is smaller than that of the catheter, creating a tight fit in the skin which may offers less leakage, greater stability and less dislocation compared with traditional (CTN) designs.

Examples of currently available catheter-over-needle systems for continuous nerve block include Contiplex® C by B Braun and E-Cath by PAJUNK. The known advantages of these systems include (i) relatively easy and quick to use, almost no additional time required, (ii) one step - i.e. once the catheter and the needle are in the right location, the needle can simply be removed and the catheter is already placed, (iii) the need to thread the catheter is eliminated, (iv) the catheter tip can be purposely placed in an exact location, without the need to be threaded, and (v) smaller puncture hole relative to catheter diameter may reduce leakage and dislodgement.

SUMMARY

Disclosed are example catheter systems for performing nerve block procedures using an over-the-needle catheter having a distal region capable of forming a helical coil shape upon advancement of the catheter and withdrawal of the needle, the coil having at least one turn. In some example embodiments, the axis of the helical coil is aligned in the direction of the longitudinal axis of the needle when the needle is partially inserted into the catheter. In other example embodiments, the axis of the helical coil may be directed at an angle relative to the longitudinal axis of the needle, such as at an angle of approximately 90 degrees. Example methods of employing the catheter for performing nerve block procedures are disclosed in which a fluid pocket of local anesthetic or other fluid is dispensed through the needle at a location adjacent to the nerve or the desired fascial plane and the distal region of the catheter is extended to form the coil within the fluid pocket.

Accordingly, in one aspect, there is provided a catheter-over-needle system comprising: a needle; and a hollow catheter having a distal opening and an inner diameter sufficiently large to accommodate insertion of the needle therethrough; the hollow catheter being configured such that in the absence of insertion of the needle within a distal region of the hollow catheter, at least a portion of the distal region forms a helical coil having at least one turn.

In some example implementations of the system, the distal region is configured such that when the needle is received within a portion of the hollow catheter without extending into the distal region, an axis of the helical coil is parallel with a longitudinal axis of the needle.

In some example implementations of the system, the distal region is configured such that when the needle is received within a portion of the hollow catheter without extending into the distal region, an angle between an axis of the helical coil and a longitudinal axis of the needle is less than 15 degrees.

In some example implementations of the system, the distal region is configured such that when the needle is received within a portion of the hollow catheter without extending into the distal region, an axis of the helical coil is perpendicular a longitudinal axis of the needle.

In some example implementations of the system, the distal region is configured such that in the absence of insertion of the needle within the distal region of the hollow catheter, the helical coil has a coil diameter that increases in a distalward direction.

In some example implementations of the system, the distal region is configured such that when the needle is received within a portion of the hollow catheter without extending into the distal region, an axis of the helical coil is angled at an angle between 45 degrees and 135 degrees relative to a longitudinal axis of the needle.

In some example implementations of the system, the distal region is configured such that in the absence of insertion of the needle within the distal region of the hollow catheter, the helical coil has a coil diameter that decreases in a distalward direction.

In some example implementations of the system, the distal region comprises a first distal portion configured to be form the helical coil in the absence of the needle therein; and a second distal portion, extending distalward from the first distal portion, the second distal portion being configured to reside in an uncoiled state in the absence of the needle therein. The second distal portion may have a length between 1 mm and 3 mm. The second distal portion may be aligned within plus or minus 10 degrees of an axis of the helical coil.

In some example implementations of the system, the hollow catheter comprises a primary lumen configured to receive the needle; and a secondary lumen configured for insertion of a guidewire.

In some example implementations of the system, a proximal region of the hollow catheter further comprises a push-tab facilitating single-handed advancement of the hollow catheter over the needle.

In some example implementations of the system, the at least a portion of the distal region that forms the helical coil comprises a plurality of orifices provided along a length thereof.

In some example implementations, the system further comprises a connection mechanism configured to removably secure the hollow catheter to the needle when the needle resides within the distal region of the hollow catheter in the absence of forming the helical coil.

In another aspect, there is provided a method of delivering a nerve block using a catheter-over-needle system as described above, the method comprising: positioning the needle within the hollow catheter such that a distal end of the needle extends through the distal opening of the hollow catheter; inserting the hollow catheter into tissue of a subject such that the distal end of the needle is adjacent to a target nerve; injecting a local anesthetic through the needle, thereby creating a fluid pocket adjacent to the nerve or the desired fascial plane; advancing the hollow catheter over the needle such that the needle is absent from the distal region of the hollow catheter and such that the distal region forms the helical coil, and such that the helical coil resides, at least in part, within the fluid pocket; removing the needle from the hollow catheter; and employing the hollow catheter to deliver additional anesthetic.

A further understanding of the functional and advantageous aspects of the disclosure can be realized by reference to the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, with reference to the drawings, in which:

FIGS. 1A-1C illustrate the catheter and needle assembly, showing the needle (FIG. 1A), the catheter in its natural coiled state (FIG. 1 B), and the catheter placed over the needle (FIG. 1C).

FIGS. 2A-2C show the details of an example needle tip, with FIG. 2A showing the catheter covering the needle while leaving only the tip exposed, FIG. 2B showing a sharp tipped needle (with cutting or noncutting bevel) with a blunt stylet, and FIG. 2C showing a blunt tipped needle with a sharp stylet.

FIG. 3A-3F show an example multi-turn coil catheter-over-the-needle system, illustrating a coiled catheter in its native state (FIG. 3A), the needle (FIG. 3B), the catheter needle assembly (FIG. 3C), the formation of a fluid pocket in close proximity to the targeted nerve of fascial plane (FIG. 3D), the deployment of the coiled catheter into the fluid pocket (FIG. 3E), the device with the needle removed and the catheter secured to the patient (FIG. 3F).

FIGS. 4A and 4B show two example axes for the orientation of the coiled portion of the catheter, with FIG. 4A showing a configuration in which the axis is perpendicular (coming out of the page) to the longitudinal axis of the needle, and FIG. 4B showing a configuration in which the axis is parallel to the longitudinal axis of the needle.

FIGS. 5A-5C show various example coil patterns of the catheter tip, with FIG. 5A showing a coil with a decreasing diameter, FIG. 5B showing a coil with an increasing diameter, and FIG. 5C showing a coil with a fixed diameter.

FIGS. 6A-6C show deployment of a fixed diameter coiled catheter over the needle.

FIGS. 7A-7C show deployment of a decreasing diameter coiled catheter over the needle.

FIGS. 8A-8C show deployment of an increasing diameter coiled catheter over the needle.

FIG. 9 illustrates an example catheter having an additional segment that extends from the distal region that is configured to form a helical coil in the absence of insertion of a needle, wherein the additional segment is configured to reside in an uncoiled state in the absence of insertion of the needle.

FIGS. 10A-10D show a catheter that has a secondary lumen that allows for insertion of a very small diameter wire through of various portions of its length, where FIG. 10A shows the proximal portion of the coiled catheter demonstrating the primary and secondary lumens and the wire in situ in the secondary lumen, FIG. 10B shows how the wire may extend the entire length of the catheter or only a portion of the length, FIG. 10C shows a wire that fits through the secondary lumen, and FIG. 10D shows a cross-section of the coiled catheter demonstrating the relationship of the primary and secondary lumens.

FIGS. 11A and 11B show that the distal end of the catheter may have a single orifice or multiple orifices.

FIG. 12 illustrates the advancement of the catheter over the needle with one hand using a small tab at the proximal end.

FIGS. 13A-13D illustrate various example implementations of connection mechanisms for securing a proximal region of the catheter to a proximal region of the needle.

DETAILED DESCRIPTION

Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure. As used herein, the terms “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms “comprises” and “comprising” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.

As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not be construed as preferred or advantageous over other configurations disclosed herein.

As used herein, the terms “about” and “approximately” are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dimensions. Unless otherwise specified, the terms “about” and “approximately” mean plus or minus 25 percent or less.

It is to be understood that unless otherwise specified, any specified range or group is as a shorthand way of referring to each and every member of a range or group individually, as well as each and every possible sub-range or sub-group encompassed therein and similarly with respect to any sub ranges or sub-groups therein. Unless otherwise specified, the present disclosure relates to and explicitly incorporates each and every specific member and combination of sub-ranges or sub-groups.

As used herein, the term "on the order of", when used in conjunction with a quantity or parameter, refers to a range spanning approximately one tenth to ten times the stated quantity or parameter.

Various example embodiments of the present disclosure seek to overcome many of the problems associated with known catheter-through- needle systems and catheter-over-the-needle systems.

Considering first the problems associated with catheter-through-needle systems, catheter dislocation and leakage at the insertion site are significant concerns when placing catheters using the traditional catheter-through-needle (CTN) method which can lead failure where the catheter is no longer providing analgesia by blocking the nerve. This dislodgement appears to result primarily from the diameter of the catheter being smaller than that of the needle used for initial skin puncture. Thus, the catheter is not held tightly by the skin, leaving space for local anesthetic to leak upon injection.

Another challenge associated with a catheter-through-needle (CTN) system is that the catheter has to be threaded through the needle and placed in close proximity of the nerve. As there is little control over the catheter tip as it is being advanced, and the catheter will follow the path with least resistance and this does not always coincide with the targeted nerve, positioning can become time consuming and cumbersome. CTN systems also require the operator to stabilize the needle with one hand while advancing the catheter with the other hand, which makes simultaneous live visualization with the ultrasound probe extremely awkward if not impossible by the same operator.

Another further drawback of CTN systems is associated with the length of the catheter that is advanced beyond the tip of the needle. The more catheter length is left in close proximity of the nerve, the less chance of accidental dislodgement. Unfortunately, “over threading” comes at the risk that the catheter may not remain in the desired location but passes beyond the nerve or is deflected away following the path of least resistance resulting in a failed block. However, if an insufficient length of catheter is in close proximity of the nerve, movement between the patient’s skin and the nerve can pull the catheter out of the effective proximity to the nerve and result in failed block.

Accordingly, disadvantages of the CTN system include (i) too many steps and thus too time consuming, (ii) inability for a single operator to simultaneously use live ultrasound imaging while threading the catheter, (iii) no control over the tip of the catheter and thus potential for over/underfeeding, (iii) discrepancies between needle tip position and final catheter position can be problematic, and (iv) leakage at the catheter insertion site.

The known catheter over-the-needle (CON) systems also suffer from several problems. For example, a very small length of the catheter of a CON system is deployed in close proximity of the neural target and as a result, even small movements by the patient could potentially displace the catheter from the target site making it ineffective. Indeed, for all currently available CON systems, the catheter is left at the needle tip without any slack. As a result, only a very small portion of the catheter is close to the target nerve, thus slight movement of the catheter may result in failure; that is, the tip of the catheter will no longer be in the proximity of the nerve. Examples of currently used CON systems include the Contiplex® C by B Braun, which provides a thin long flexible needle which is difficult to control and a relative stiff catheter, and the E-Cath by PAJUNK, which requires insertion of a second catheter through a cannula that has been placed close to the nerve and still suffers from inadequate catheter length (slack) in the close proximity of the nerve.

The present inventor set out to identify improvements and solutions that would address the aforementioned problems associated with conventional CTN and CON nerve block systems and procedures. As explained below, the present inventor realized that a conventional CON design could be significantly improved by the incorporation of distal region of the catheter that assumes a multiple-turn coil upon withdrawal of the needle.

Referring now to FIGS. 1A-1C, an example CON continuous nerve block system is shown. The example CON continuous nerve block system includes a needle 100 and a catheter 110, where the needle is extendable within a lumen of the catheter. The distal region 115 of the catheter 110 has a shape-memory property that forms a helical coil when the needle 100 is withdrawn from the lumen, as shown in FIG. 1 B. Accordingly, when the needle 100 does not reside within the distal region 115 of the example catheter 110, the distal region assumes a shape having at least one full coil turn (i.e. >360 degrees), thereby forming a helical coil.

The distal region 115 of the catheter 110 is sufficiently flexible such that the coil collapses to a linear configuration when the distal region 104 of the needle 100 is received within the distal region 115 of the catheter 110 (as shown in FIG. 1C). In some example implementations, the distal end 115 of the catheter 110 may be shaped to include 1 -3 coils turns (e.g. 360 to 1080 degrees) in the absence of the needle. The diameter of each coil turn may be in the range of 2-15 mm. The length of the coiled section, measured longitudinally along the catheter 110, may range between 10 -50 mm.

In some example implementations, the length of the catheter 110 may range between 5 to 15 cm. In some example implementations, the inner diameter of the catheter 110 may lie within the range of 16-23 GA. The length and diameter of the catheter are selected to be appropriate to facilitate passage of needle 100 therethrough, such that when fully inserted into the catheter 110, the distal end 104 of the needle 100 extends through a distal opening in the catheter 110. The length of the catheter 110 is therefore able to cover the entire length of the needle 100 except for the very distal end 104 (e.g. 1 -3 mm) (as illustrated in FIG. 1 C and FIG. 2A). This also allows for the catheter 110 to act as the insulation for the needle 100 limiting the electrical conduction to the exposed distal tip 104 of the needle 100. The internal diameter of the catheter 110 is selected such that the catheter 110 is able to fit over the needle 100 yet also be smoothly deployable (advanced off the needle) when required. The example needle 100 is a hollow elongate metal tube having a proximal end 102, distal end 104 and a central longitudinal portion 106. In some example implementations, the length of the needle 100 may range between 5 to 15 cm and the outer diameter of the needle may be 17-24 GA. The needle 100 is capable of electrical current conduction and may be formed from a suitable metal, metal alloy or other electrically conductive and rigid material. Electrical current conduction is only required if electrical stimulation and localization of the nerve or neural element is required otherwise any rigid and preferably echogenic material could be used.

As shown in FIGS. 1A and 1C, the needle 100 may include one or more supports 120 near its proximal end that allow for the operator to ergonomically hold and maneuver the needle easily. An example of such supports 120 are fixed wings. The needle 100 may include one or more length graduation markings. As shown in FIGS. 1A-1C, the proximal end 102 of the needle 100 is configured for fluid connection. For example, as shown in FIG. 1C, the proximal end 102 of the needle 100 may be connected to an extension set via a Luer lock design 130. In one example implementation, a syringe 132 may be used to inject the local anesthetic or desired fluid through the extension set 134 and needle to generate the fluid pocket at the target. The extension set may be a simple tube 134 that connects between the needle 100 and syringe 132 or may include any manner of adapter for enabling the procedure. The proximal end 102 also accommodates an electrically conductive wire 140 which may be coupled through an appropriate connector 142 to an appropriate nerve stimulator for supplying an electrical current to the needle (as shown in FIGS. 1A and 1C). The distal end 104 of the needle 100 is configured for insertion through tissue and into the vicinity of a nerve or plexus of nerves. In some cases, the needle 100 is a straight needle with short or standard beveled (cutting or noncutting) sharp tip 150 with varying degrees of beveling at the distal end (e.g. as shown in three different views in FIG. 2A). The distal portion 104 of the needle extends beyond the catheter 110.

In one example embodiment shown in FIG. 2B, a sharp tipped needle 100 may be utilized with a blunt stylet 160 that protrudes from the distal end needle by 1-5 mm. This configuration may be beneficial in allowing an operator to load the coiled catheter onto the needle prior to use or if required for reloading the catheter onto the needle without damaging the inside of the coiled catheter by the sharp tip 162 of the needle. In another example embodiment shown in FIG. 2C, the needle 100 may have a noncutting (not sharp) tip 164 allowing the catheter to be loaded onto the needle without damaging the catheter. In this scenario, a stylet with a cutting tip 166 is employed and once inserted into the needle, the whole system can be advanced through the skin and towards the target. Once the targeted neural structure is reached the sharp stylet 166 is removed and the catheter can be advanced over the blunt needle 100 and left at the desired depth and location and the needle is then retracted.

The distal end of the needle or alternatively the entire length of the needle may be echogenic and thus readily visible during the ultrasound guidance of the needle and catheter. This could be accomplished, for example, by an engraved pattern/etching in the needle that maximizes ultrasound wave reflection back toward the probe. Two non-limiting example types of echogenic etchings are in common use, dihedral groove etched into the needle surface or tetrahedral reflector that has a four-sided intermittent etching in the shaft of the needle. Both can be manipulated to optimize the reflection from sound waves of different frequencies. The needle may include a marking that indicates depth of insertion as well as a desired location to which the proximal end of the catheter is advanced relative to the needle prior to removal of the needle.

The following example embodiment illustrates a non-limiting and example method involving the use of a CON catheter system having a distal shape-memory coil 115 during a nerve block procedure, as illustrated in FIGS. 3A-3F. The catheter 110 (shown in FIG. 3A) may be preloaded on the needle 100 (the needle shown in FIG. 3B) or loaded onto the needle prior to use by the operator, where the pre-loaded configuration is shown in FIG. 3C.

After prepping the skin over the insertion site, the target is scanned with any suitable ultrasound probe. The ultrasound probe is held in one hand by the operator and can be used throughout the procedure. The catheter system (needle 100 and catheter 110 as one unit) are introduced and advanced towards the target by the operator’s other hand. The needle/catheter assembly is an echogenic device in that it is readily “detected” by the probe during ultrasound imaging. Once the operator positions the needle at the target (e.g., using ultrasound guidance or anatomical landmarks) confirmation of the target can also be achieved using electrical nerve stimulation if so desired. The catheter 110 on the needle 100 can act as an electrical insulation in effect making the needle into an “insulated needle” and allowing for electrical nerve stimulation via only the tip of the needle. Once the target has been reached local anesthetic or D5W (or any desired fluid) may be injected through the needle 100 creating a fluid pocket 170 at the tip of the needle 100 adjacent to the targeted nerve 175 or the desired location in the fascial plane, as shown at FIG. 3D. The catheter 110 can now be advanced over the needle 100 into the fluid pocket 170 created in close proximity of the nerve 175 to the desired length. Since the tip of the catheter 110 has the ability to curl 115 at its distal end, it remains within close proximity of the target, residing at least partially within the fluid pocket 175, as shown in FIG. 3E. Once the catheter 110 is advanced (e.g., about 1-4 cm) the needle 110 is removed while the operator stabilizes the catheter, as shown in FIG. 3F. This method allows for more of the catheter 110 to remain close to the target, and less likely to be inadvertently dislodged. The catheter 110 may then be employed for continuous delivery of additional anesthetic.

The present example embodiments that facilitate the formation of a helical coil having at least one turn upon withdrawal of the needle address the aforementioned shortcomings of known CON and CTN system. In particular, a coiled-tip catheters of the present example embodiments retain their distal shape at the tip and reduce the risk of dislocation of the catheter tip from the target site as more of the catheter can be threaded in close proximity of the nerve. In contrast to known nerve block catheter designs that employ a hooked (“pigtail”) distal region with only a partial turn that loops back toward the proximal end of the catheter, the present example embodiments provide a catheter having a distal end configured, when the needle is not present, to form a helical coil having at least one full coil turn (i.e. >360 degrees).

Currently available pigtail catheters employ a pigtail having less than one 360 degree turn, and are provided in the form of a catheter-through-the- needle system. Such catheters are plagued by aforementioned shortcomings of this design as well as the length limitation of a single pigtail. For example, one known catheter-over-the-needle system having a curved distal end (with a curve of only 80-110 degrees) in disclosed in US Patent No. 8,986,283.

The curved distal end of this catheter is designed to hook around neural structures, which is a feature that may not be desirable since insertion around a nerve and especially removal of the catheter may pose risk of damaging the nerve especially if the catheter is left in situ for a significant length of time due to possibility of an inflammatory reaction and formation of adhesions. Furthermore, this design is at risk of dislodgement as there is still limited length of the catheter in close proximity of the nerve. This curved catheter over the needle system that is designed to curve around a nerve therefore offers no advantage in fascial plane blocks.

In stark contrast, the example embodiments of the present disclosure provide a multi-turn coil CON system that can be advantageously used in continuous regional anesthesia and peripheral nerve blocks. Indeed, a multi turn coil CON system may be effective in addressing many of the aforementioned limitations of conventional CTN systems. This improved multi turn coil configuration may be beneficial, for example, in fascial plane blocks due to ease of use and slack catheter left in the desired plane and reduced risk of dislodgement. Furthermore, the present example embodiments enable faster and more efficient use and can be operated by a single operator using one hand for visualization by ultrasound and the other hand for manipulating the catheter and needle assembly to its target, while using the same hand to deploy the catheter under live and direct ultrasound visualization. The multi turn coiled CON design also allows for a significant length of the catheter to remain at the exact desired location.

Many of the example embodiments described herein illustrate an example configuration in which the axis of the distal coiled region of the catheter is coaxial, parallel, or approximately aligned with the axis of the needle when the needle is withdrawn from within the catheter lumen (e.g. when the needle resides within catheter lumen but does not extend into the distal coil region). An example of a distal coil region 115 of the catheter having a coaxial configuration is shown in FIG. 4B, where the coil axis 200 is shown coaxial with the longitudinal axis 210 of the needle. In some example embodiments, the angle between the coil axis and the longitudinal axis of the needle is less than 5 degrees, less than 10 degrees, or less than 15 degrees (the angle between axes that do not intersect may be determined after relative translation of the axes such that they lie within a coming plane). “Approximately aligned”, as used herein, refers to a configurations in which the longitudinal axis of the needle, after the needle is withdrawn from distal region of the catheter and the full coil shape is recovered, passes through the coil and extends through the distal opening of the coil without being coaxial with or parallel to an axis defined by the coil.

In other example embodiments, the distal coil region of the catheter may be shaped such that an axis defined by the coil is not coaxial or near- axial with the longitudinal axis of the needle as the needle is withdrawn, and the coil axis may be oriented at a larger angle relative to the needle axis, such as in a perpendicular or approximately perpendicular (e.g. angled within 45- 135 degrees, or between 70-110 degrees) configuration. An example of such a configuration is shown in FIG. 4A, in which the coil axis 205 is perpendicular to the needle axis 210.

Ultrasound imaging of a nerve is usually performed in the short axis of the nerve, with the ultrasound beam intersecting the nerve such that a circular cross-section of the nerve is seen in the ultrasound image. In such a case, the needle is advanced toward the nerve in parallel with the ultrasound beam (i.e. the needle lies within the plane of the ultrasound beam). Accordingly, when the needle is placed close to the nerve and the catheter is advanced off of the needle, then in the case of a catheter coil having a coil axis that is perpendicular (FIG. 4A) or significantly angled (e.g. an angle between 45 and 135 degrees) relative to the longitudinal axis of the needle, the catheter coil could potentially wrap around the nerve, or the catheter coil may be deflected away from the nerve, since the nerve is right in front the catheter. However, in the case of a coil axis that is coaxial, parallel or approximately aligned with the needle axis, such as the example coaxial case shown in FIG. 4B, the coil axis configuration may reduce the chance of catheter inadvertently coiling around a nerve or neural structure as the neural structure is approached in the short axis.

In some example embodiments, the distal region 115 of the catheter 110 may have a shape that forms a coil with a constant diameter, as shown in FIG. 1 B, FIG. 3A and FIG. 3E. In other example embodiments, the distal region of the catheter may have a shape that forms a coil with diameter that varies along at least a portion of the coil. Non-limiting examples of such embodiments are shown in FIGS. 5A-5C, 6A-6C, 7A-7C and 8A-8C, which show coils in which the diameter progressively increases or decreases.

FIG. 9 illustrates an example catheter having an additional segment 118 that extends from the distal region 115 that is configured to form a helical coil in the absence of insertion of a needle, wherein the additional segment 118 is configured to reside in an uncoiled state in the absence of insertion of the needle (e.g. a linear, elongate or straight segment). In some example implementations, the additional segment 118 that is configured to reside in an uncoiled state in the absence of insertion of the needle may have a length ranging from 1 to 3 mm. The additional segment may be formed such that in the absence of insertion of the needle, the additional segment is aligned within ± 30°, ± 20°, ± 10° or ± 5°, of the coil axis.

In some example embodiments, the coil pitch, which is the distance between successive coil turns along the coil axis, may be constant along the extent of the coil. In other example embodiments, the coil pitch may be increasing or decreasing in a distal direction. In some example embodiments, the coil pitch may be constant and larger than the smallest diameter of the coil. In other example embodiments, the coil pitch may be constant and smaller than the smallest diameter of the coil. In other example embodiments, the coil pitch may be constant and larger than the largest diameter of the coil. In other example embodiments, the coil pitch may be constant and smaller than the largest diameter of the coil. In example embodiments involving an increasing or decreasing coil diameter, at least a portion of the coil may have a pitch that is less than one half the smallest coil diameter, less than one third of the smallest coil diameter, less than one quarter of the smallest coil diameter, less than one fifth of the smallest coil diameter, or less than one tenth of the smallest coil diameter. A range of medical grade polymers may be used for the construction of the catheter, including fluorothermoplastic (such as PTFE), nylon, braided nylon, polyurethane, silicone, polyvinyl chloride (PVC), Teflon, polyamide, polyester, elastomer, PET, thermoplastic, hydrocoat, metal alloy, braided metal (such as Nitinol), or other material silicone rubber, or other material such as reinforcing coil/filament or combination of materials that would result in an abrasion and kink/crush resistance. The coils at the distal tip of the catheter can be made of shape retaining material that can be thermoformed or braided into the desired shape. Alternatively, the coiling of the catheter tip can be achieved by embedded helical metal coils or braided metal embedded within the catheter wall.

The catheter may have different stiffness (durometer) throughout its length. The distal region (tip) of the catheter, which has the ability to curl into a helix in the absence of the insertion of the needle, may be made of softer material with more flexible preventing it from piercing through unintended tissue, damaging any neural structure or advancing further than the pocket of fluid created the tip of the assembly when deployed. The catheter may also have more flexibility at its proximal end allowing it to be more easily secured to the patient at a convenient location, for example without kinking of compromised flow through the catheter.

The body of the catheter may have a stiffness that varies over at least a portion of its length. For example, the catheter may have a stiffness that increases over at least a portion of its length, which may be beneficial in providing enough rigidity to advance the catheter over the needle effectively. This could be achieved, for example, with different composition or density of material through the length of the catheter or by wire braiding (helical coils) embedded into the catheter. This wire braiding may have varying helical coil/filament density throughout the length of the catheter.

Alternatively, this variable stiffness could be achieved by a wire (removable or fixed) inserted into a secondary lumen along variable lengths or the entire length of the catheter. An example implementation of such an embodiment is shown in FIGS. 10A-10D, which show a catheter 110 that has a secondary lumen 300 that allows for insertion of a very small diameter wire 310 through of various portions of its length. FIG. 10A shows the proximal portion of the coiled catheter 110 demonstrating the primary 305 and secondary 300 lumens and the wire 310 in situ in the secondary lumen. FIG. 10B shows how the wire 310 may extend the entire length of the catheter 110 or only a portion of the length. FIG. 10C shows a wire 310 that fits through the secondary lumen. FIG. 10D shows a cross-section of the coiled catheter 110 demonstrating the relationship of the primary 305 and secondary 300 lumens. The distal end of the secondary lumen 300 may be closed off such that it is not in fluid communication with the outside.

In some example embodiments, it may be desirable to also render the catheter echogenic to aid in the guidance procedure and to ultrasonically verify placement of the catheter after removal of the needle. In this regard, the sheath may contain any manner etching or echogenic material, such as metal threads or flakes, formed with the sheath or subsequently added to the surface of the sheath.

The distal coiled end 115 of the catheter 110 may have one orifice 350 (at the tip or anywhere along the distal end) or multiple orifices 351 to allow for either precise or more disperse deposition of local anesthetic in the targeted area depending on the intended use (as illustrated in FIGS. 11 A and11 B).

As shown in FIG. 12, the proximal hub 112 of the catheter 110 may have a push-off tab 114 at the proximal end which may allow for a single- handed advancement of the catheter over the needle. The push-off tab 114 may be employed advance the catheter 110 using the index finger, as shown. This allows a single operator to maintain visualization of the needle/catheter and the target nerve while holding the ultrasound probe in one hand and may more easily manipulate and deploy the catheter using the other hand.

In some example embodiments, the proximal region of the catheter may be configured to facilitate attachment to the patient using an adhesive stabilization and/or fixation device. For example, as shown in FIG. 12, the proximal end of the catheter may include flexible perforated wings 116 that facilitate secure fixation of the catheter to the patient.

In some example embodiments, the proximal region of the catheter may include a connector facilitating connection of the proximal end of the catheter to tubing and an infusion pump, for example, as shown in FIG. 3F.

An example of a suitable connector is a low-profile Luer lock connector.

It may be beneficial for the catheter to be well secured while being loaded onto the needle as target localization may require a few attempts where the needle/catheter assembly is advanced and withdrawn hence the catheter should remain securely in place on the needle and not slide off. The proximal hub of the catheter may be configured to removably engage with the needle, for example, via a frictional fit or another engagement mechanism such as, but not limited to, a clip or other securing mechanism that extends from the needle housing to the catheter which can be easily disengaged single handedly by the operator before catheter deployment (e.g. before the catheter is extended to form the helical coil). In one example implementation, an elastically-biased (e.g. spring loaded) member (e.g. tab) may be provided on the proximal end of the catheter that can be lifted to release the catheter from the needle in order to advance the catheter forward. In an alternative example implementation, the catheter may include a rotational lock, such that rotation of the catheter in one direction unlocks the catheter from engagement with the needle. Example implementations of such an embodiment are illustrated in FIGS. 13A and 13B, which show male (400 and 405, respectively) and female (410 and 415, respectively) connectors for connecting the catheter 110 (at the proximal hub 112) to the needle 100 (at the proximal end of the needle 102). Another example implementation is illustrated in FIGS. 13C and 13D in which a clip 720 residing on the proximal end 102 (a proximal hub) of the needle 100 is connectable to a protuberance 725 residing on the proximal hub 112 of the catheter 110. The catheter, once placed over the needle, acts as an electrical insulator for the needle, thereby rendering it electrically insulated throughout its length and limiting the current stimulation only to the tip of the needle.

The catheter may be preloaded onto the needle (e.g. in a ready to use kit) or may alternatively be loaded safely over the needle, with the stylet in place, by the operator.

Although the preceding example embodiments have been described within the context of medical procedures involving nerve blocks, it will be understood that the present example embodiments may be employed or adapted for other applications. For example, example embodiments of the present disclosure may be employed for drainage of an existing fluid/air pocket when its desirable to leave behind a catheter that has less chance of dislodgement for continuous drainage. In another example application, a catheter provided according to one of the aforementioned example embodiments may be employed for administering continuous localized medication into any tissue or cavity within the body, especially for cases in which a catheter with less chance of dislodgement than a simple pigtail catheter maybe desired.

The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.